Calibration of a Playback Device Based on an Estimated Frequency Response

ABSTRACT

An example playback device is configured to receive a first stream of audio comprising source audio content to be played back by the playback device and record, via one or more microphones of the playback device, an audio signal output by the playback device based on the playback device playing the source audio content. The playback device is also configured to determine a transfer function between a frequency-domain representation of the first stream of audio and a frequency-domain representation of the recorded audio signal, and then determine an estimated frequency response of the playback device based on a difference between (i) the transfer function and (ii) a self-response of the playback device, where the self-response of the playback device is stored in a memory of the playback device. Based on the estimated frequency response, the playback device is configured to determine an acoustic calibration adjustment and implement the acoustic calibration adjustment.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 16/665,415, filed on Oct. 28, 2019, entitled“Calibration of a Playback Device Based on an Estimated FrequencyResponse,” which is a continuation of and claims priority to U.S. patentapplication Ser. No. 15/229,693, filed on Aug. 5, 2016, entitled“Calibration of a Playback Device Based on an Estimated FrequencyResponse,” the contents of each of which are hereby incorporated byreference in their entirety for all purposes.

FIELD OF THE DISCLOSURE

The disclosure is related to consumer goods and, more particularly, tomethods, systems, products, features, services, and other elementsdirected to media playback or some aspect thereof.

BACKGROUND

Options for accessing and listening to digital audio in an out-loudsetting were limited until in 2003, when SONOS, Inc. filed for one ofits first patent applications, entitled “Method for Synchronizing AudioPlayback between Multiple Networked Devices,” and began offering a mediaplayback system for sale in 2005. The Sonos Wireless HiFi System enablespeople to experience music from many sources via one or more networkedplayback devices. Through a software control application installed on asmartphone, tablet, or computer, one can play audio in any room that hasa networked playback device. Additionally, using the control device, forexample, different songs can be streamed to each room with a playbackdevice, rooms can be grouped together for synchronous playback, or thesame song can be heard in all rooms synchronously.

Given the ever growing interest in digital media, there continues to bea need to develop consumer-accessible technologies to further enhancethe listening experience.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technologymay be better understood with regard to the following description,appended claims, and accompanying drawings where:

FIG. 1 shows an example playback system configuration in which certainembodiments may be practiced;

FIG. 2 shows a functional block diagram of an example playback device;

FIG. 3 shows a functional block diagram of an example control device;

FIG. 4 shows an example control device interface;

FIG. 5 shows an example network configuration in which certainembodiments may be practiced;

FIG. 6 shows a functional block diagram of an example network microphonedevice;

FIG. 7 shows an example environment in which certain embodiments may bepracticed;

FIG. 8 shows an example flow diagram of functions associated withcalibrating an example playback device;

FIG. 9 shows an example of frequency binning;

FIG. 10 shows an example audio pipeline of an example playback device;and

FIG. 11 shows an example graphical user interface associated withcalibration of an example playback device.

The drawings are for the purpose of illustrating example embodiments,but it is understood that the embodiments are not limited to thearrangements and instrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

Rooms have certain acoustics which define how sound travels within theroom. For example, a size and shape of the room may affect how soundreflects off a wall and ceiling of the room. As another example, typesof surfaces in the room may affect how sound travels in the room. Hardsurfaces such as wood or glass may reflect sound whereas soft surfacessuch as leather or fabric may absorb sound.

An audio playback device may be located in the room. The audio playbackdevice may have one or more speakers for playing audio content in theroom. It may be desirable to calibrate (e.g., adjust) acoustics of theaudio playback device so as to improve a listening experience in theroom.

The calibration may be based on audio content played by the audioplayback device. For example, the audio content may be music provided bya music content provider such as Spotify, Pandora, Amazon Music, amongothers, via a wide area network such as the Internet. The calibrationmay involve receiving a first stream of audio and a second stream ofaudio. The first stream of audio may be source audio content to beplayed back by the audio playback device. The second stream of audio maybe a recording of an audio signal output by the audio playback devicebased on the audio playback device playing the source audio content. Afrequency response of an audio playback device may be estimated based onthe source audio content and the recording of the audio content, whichmay then be used to adjust acoustics of the audio playback device.

The calibration may be performed during a discrete or continuouscalibration period. The discrete calibration period may be a calibrationof the audio playback device that is performed as a result of acondition being met. For example, the condition may be that the audioplayback device is being setup for use. Additionally, or alternatively,the condition may be that the audio playback device has not beencalibrated before or a previous attempt to calibrate the audio playbackdevice was unsuccessful. Still additionally, or alternatively, thecondition may be that the audio playback device has moved or changedorientation. On the other hand, the continuous calibration period may bea calibration of the audio playback device that continues so long as theaudio playback device plays audio content. Unlike the discretecalibration process, the calibration of the audio playback device may begenerally ongoing and/or continuous, e.g., as a background process,while the audio playback device plays audio content.

The discrete or continuous calibration process may begin with the audioplayback device playing source audio content. The source audio contentmay be spectral content such as music. The music may have frequenciessubstantially covering a render-able frequency range of the playbackdevice, a detectable frequency range of the microphone, and/or anaudible frequency range for an average human.

The playback of the source audio content may take the form of the audioplayback device outputting an audio signal. This audio signal output bythe playback device may be recorded.

The audio playback device may have a microphone in proximity to theaudio playback device. For example, the microphone may be co-locatedphysically on or in the playback device or wired or wirelessly connectedto the audio playback device. This microphone may record the audiosignal output by the audio playback device.

In another example, an audio signal output by the audio playback devicemay be recorded at a spatial location different from the spatiallocation of the audio playback device. The different spatial locationmay be where another device (such as a playback device, a controllerdevice, or a network microphone device, among other examples) islocated. Via its microphone, the other device may record the audiosignal output by the audio playback device.

Acoustic echo cancellation is a process for cancelling reflectedacoustic sounds from a speaker that are recorded by a microphone. Theacoustic cancellation algorithm may be modified to determine a transferfunction between a frequency response of the source audio content and afrequency response of the recorded audio signal output by the audioplayback device. In turn, the transfer function and a self-response ofthe audio playback device in an anechoic chamber may be used todetermine an estimated frequency response of the audio playback device.In the case of a controller device recording the audio signal output bythe audio playback device, this estimated frequency response may be anapproximation of the response curve as described in U.S. patentapplication Ser. No. 14/864,393, entitled “Facilitating Calibration ofan Audio Playback Device”, the contents of which is herein incorporatedby reference in its entirety. In the case of the audio playback deviceitself recording the audio signal output by the audio playback device,this estimated frequency response may represent a self-response of theaudio playback device as described in U.S. patent application Ser. No.15/096,827, entitled “Calibration of Audio Playback Devices”, thecontents of which is herein incorporated by reference in its entirety.Other arrangements are also possible.

The estimated frequency response may be used to calibrate (e.g. adjust)acoustics of the audio playback device. For example, the estimatedfrequency response may be used to select an audio processing algorithmsuch as a filter or equalization to adjust acoustic settings of theaudio playback device. U.S. patent application Ser. No. 14/481,511,entitled “Playback Device Calibration”, the contents of which is hereinincorporated by reference in its entirety, discloses various audioprocessing algorithms to adjust acoustics of an audio playback device.The filter or equalization may be applied to audio content played by theaudio playback device until such time that the filter or equalization isno longer valid or not needed.

In one example, functions associated with the disclosed calibration maybe coordinated and at least partially performed by an audio playbackdevice, such as one of the one or more audio playback devices to becalibrated for the playback environment. The audio playback device maycalculate an estimated frequency response based on a first stream andsecond stream of audio and adjust acoustics of the audio playback devicebased on the estimated frequency response.

In another example, functions associated with the disclosed calibrationmay be coordinated and at least partially performed by a computingdevice. The computing device may be a server associated with a mediaplayback system that includes one or more audio playback devices. Thecomputing device may calculate an estimated frequency response based ona first stream and second stream of audio and adjust acoustics of theaudio playback device based on the estimated frequency response.

In yet another example, functions associated with the disclosedcalibration may be coordinated and at least partially performed by acontroller device. The controller device may be used to control theaudio playback device. The controller device may calculate an estimatedfrequency response based on a first stream and second stream of audioand adjust acoustics of the audio playback device based on the estimatedfrequency response.

Moving on from the above illustration, an example embodiment may includea method which comprises receiving, via a wide area network (WAN), afirst stream of audio comprising source audio content to be played backby the audio playback device; receiving a second stream of audiocomprising a recording of an audio signal output by the audio playbackdevice based on the audio playback device playing the source audiocontent; calculating an estimated frequency response of the audioplayback device based on the received first stream of audio and thereceived second stream of audio; and adjusting acoustics of the audioplayback device based on the estimated frequency response. Calculatingan estimated frequency response of an audio playback device based on thereceived first stream of audio and second stream of audio may comprisedetermining a transfer function between a frequency response of thefirst stream of audio and a frequency response of the second stream ofaudio. Determining a transfer function between a frequency response ofthe first stream of audio and a frequency response of the second streamof audio may comprise determining whether the transfer function hasconverged. The estimated frequency response of an audio playback devicemay be calculated based on an acoustic echo cancellation algorithm.Receiving, via a wide area network (WAN), a first stream of audio maycomprise receiving, via the WAN, music from a music service provider.The method may further comprise determining that the audio playbackdevice has moved. The estimated frequency response may be calculated inresponse to determining that the audio playback device has moved. Themethod may further comprise determining a spectral coverage of thesource audio content prior to calculating the estimated frequencyresponse. The method may further comprise playing back the source audiocontent based on the adjusted acoustics. The audio signal output by theaudio playback device may be recorded at a spatial location differentfrom the audio playback device. The audio signal output by the audioplayback device may be recorded by the audio playback device.

Another example embodiment may include a tangible non-transitorycomputer readable storage medium including instructions executable by aprocessor to cause the processor to implement a method of receiving, viaa wide area network (WAN), a first stream of audio comprising sourceaudio content to be played back by the audio playback device; receivinga second stream of audio comprising a recording of an audio signaloutput by the audio playback device based on the audio playback deviceplaying the source audio content; calculating an estimated frequencyresponse of the audio playback device based on the received first streamof audio and the received second stream of audio; and adjustingacoustics of the audio playback device based on the estimated frequencyresponse. The instructions for calculating an estimated frequencyresponse of an audio playback device based on the received first streamof audio and second stream of audio may comprise determining a transferfunction between a frequency response of the first stream of audio and afrequency response of the second stream of audio. The instructions fordetermining a transfer function between a frequency response of thefirst stream of audio and a frequency response of the second stream ofaudio may comprise determining whether the transfer function hasconverged. The tangible non-transitory computer readable storage mayfurther comprise instructions for determining that the audio playbackdevice has moved. The estimated frequency response may be calculated inresponse to determining that the audio playback device has moved. Thetangible non-transitory computer readable storage may further compriseinstructions for determining a spectral coverage of the source audiocontent prior to calculating the estimated frequency response. Thetangible non-transitory computer readable storage may further compriseinstructions for playing back the source audio content based on theadjusted acoustics. The audio signal output by the audio playback devicemay be recorded at a spatial location different from the audio playbackdevice. The audio signal output by the audio playback device may berecorded by the audio playback device. The instructions for receiving,via a wide area network (WAN), a first stream of audio may comprisereceiving music from a music service provider via the WAN. The estimatedfrequency response of an audio playback device may be calculated basedon an acoustic echo cancellation algorithm.

II Example Operating Environment

FIG. 1 shows an example configuration of a media playback system 100 inwhich one or more embodiments disclosed herein may be practiced orimplemented. The media playback system 100 as shown is associated withan example home environment having several rooms and spaces, such as forexample, a master bedroom, an office, a dining room, and a living room.As shown in the example of FIG. 1, the media playback system 100includes playback devices 102-124, control devices 126 and 128, and awired or wireless network router 130.

Further discussions relating to the different components of the examplemedia playback system 100 and how the different components may interactto provide a user with a media experience may be found in the followingsections. While discussions herein may generally refer to the examplemedia playback system 100, technologies described herein are not limitedto applications within, among other things, the home environment asshown in FIG. 1. For instance, the technologies described herein may beuseful in environments where multi-zone audio may be desired, such as,for example, a commercial setting like a restaurant, mall or airport, avehicle like a sports utility vehicle (SUV), bus or car, a ship or boat,an airplane, and so on.

a. Example Playback Devices

FIG. 2 shows a functional block diagram of an example playback device200 that may be configured to be one or more of the playback devices102-124 of the media playback system 100 of FIG. 1. The playback device200 may include a processor 202, software components 204, memory 206,audio processing components 208, audio amplifier(s) 210, speaker(s) 212,a network interface 214 including wireless interface(s) 216 and wiredinterface(s) 218, and microphone(s) 220. In one case, the playbackdevice 200 may not include the speaker(s) 212, but rather a speakerinterface for connecting the playback device 200 to external speakers.In another case, the playback device 200 may include neither thespeaker(s) 212 nor the audio amplifier(s) 210, but rather an audiointerface for connecting the playback device 200 to an external audioamplifier or audio-visual receiver.

In one example, the processor 202 may be a clock-driven computingcomponent configured to process input data according to instructionsstored in the memory 206. The memory 206 may be a tangiblecomputer-readable medium configured to store instructions executable bythe processor 202. For instance, the memory 206 may be data storage thatcan be loaded with one or more of the software components 204 executableby the processor 202 to achieve certain functions. In one example, thefunctions may involve the playback device 200 retrieving audio data froman audio source or another playback device. In another example, thefunctions may involve the playback device 200 sending audio data toanother device or playback device on a network. In yet another example,the functions may involve pairing of the playback device 200 with one ormore playback devices to create a multi-channel audio environment.

Certain functions may involve the playback device 200 synchronizingplayback of audio content with one or more other playback devices.During synchronous playback, a listener will preferably not be able toperceive time-delay differences between playback of the audio content bythe playback device 200 and the one or more other playback devices. U.S.Pat. No. 8,234,395 entitled, “System and method for synchronizingoperations among a plurality of independently clocked digital dataprocessing devices,” which is hereby incorporated by reference, providesin more detail some examples for audio playback synchronization amongplayback devices.

The memory 206 may further be configured to store data associated withthe playback device 200, such as one or more zones and/or zone groupsthe playback device 200 is a part of, audio sources accessible by theplayback device 200, or a playback queue that the playback device 200(or some other playback device) may be associated with. The data may bestored as one or more state variables that are periodically updated andused to describe the state of the playback device 200. The memory 206may also include the data associated with the state of the other devicesof the media system, and shared from time to time among the devices sothat one or more of the devices have the most recent data associatedwith the system. Other embodiments are also possible.

The audio processing components 208 may include one or moredigital-to-analog converters (DAC), an audio preprocessing component, anaudio enhancement component or a digital signal processor (DSP), and soon. In one embodiment, one or more of the audio processing components208 may be a subcomponent of the processor 202. In one example, audiocontent may be processed and/or intentionally altered by the audioprocessing components 208 to produce audio signals. The produced audiosignals may then be provided to the audio amplifier(s) 210 foramplification and playback through speaker(s) 212. Particularly, theaudio amplifier(s) 210 may include devices configured to amplify audiosignals to a level for driving one or more of the speakers 212. Thespeaker(s) 212 may include an individual transducer (e.g., a “driver”)or a complete speaker system involving an enclosure with one or moredrivers. A particular driver of the speaker(s) 212 may include, forexample, a subwoofer (e.g., for low frequencies), a mid-range driver(e.g., for middle frequencies), and/or a tweeter (e.g., for highfrequencies). In some cases, each transducer in the one or more speakers212 may be driven by an individual corresponding audio amplifier of theaudio amplifier(s) 210. In addition to producing analog signals forplayback by the playback device 200, the audio processing components 208may be configured to process audio content to be sent to one or moreother playback devices for playback.

Audio content to be processed and/or played back by the playback device200 may be received from an external source, such as via an audioline-in input connection (e.g., an auto-detecting 3.5 mm audio line-inconnection) or the network interface 214.

The network interface 214 may be configured to facilitate a data flowbetween the playback device 200 and one or more other devices on a datanetwork. As such, the playback device 200 may be configured to receiveaudio content over the data network from one or more other playbackdevices in communication with the playback device 200, network deviceswithin a local area network, or audio content sources over a wide areanetwork such as the Internet. In one example, the audio content andother signals transmitted and received by the playback device 200 may betransmitted in the form of digital packet data containing an InternetProtocol (IP)-based source address and IP-based destination addresses.In such a case, the network interface 214 may be configured to parse thedigital packet data such that the data destined for the playback device200 is properly received and processed by the playback device 200.

As shown, the network interface 214 may include wireless interface(s)216 and wired interface(s) 218. The wireless interface(s) 216 mayprovide network interface functions for the playback device 200 towirelessly communicate with other devices (e.g., other playbackdevice(s), speaker(s), receiver(s), network device(s), control device(s)within a data network the playback device 200 is associated with) inaccordance with a communication protocol (e.g., any wireless standardincluding IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4Gmobile communication standard, and so on). The wired interface(s) 218may provide network interface functions for the playback device 200 tocommunicate over a wired connection with other devices in accordancewith a communication protocol (e.g., IEEE 802.3). While the networkinterface 214 shown in FIG. 2 includes both wireless interface(s) 216and wired interface(s) 218, the network interface 214 may in someembodiments include only wireless interface(s) or only wiredinterface(s).

The microphone(s) 220 may be arranged to detect sound in the environmentof the playback device 200. For instance, the microphone(s) may bemounted on an exterior wall of a housing of the playback device. Themicrophone(s) may be any type of microphone now known or later developedsuch as a condenser microphone, electret condenser microphone, or adynamic microphone. The microphone(s) may be sensitive to a portion ofthe frequency range of the speaker(s) 220. One or more of the speaker(s)220 may operate in reverse as the microphone(s) 220. In some aspects,the playback device 200 might not have microphone(s) 220.

In one example, the playback device 200 and one other playback devicemay be paired to play two separate audio components of audio content.For instance, playback device 200 may be configured to play a leftchannel audio component, while the other playback device may beconfigured to play a right channel audio component, thereby producing orenhancing a stereo effect of the audio content. The paired playbackdevices (also referred to as “bonded playback devices”) may further playaudio content in synchrony with other playback devices.

In another example, the playback device 200 may be sonicallyconsolidated with one or more other playback devices to form a single,consolidated playback device. A consolidated playback device may beconfigured to process and reproduce sound differently than anunconsolidated playback device or playback devices that are paired,because a consolidated playback device may have additional speakerdrivers through which audio content may be rendered. For instance, ifthe playback device 200 is a playback device designed to render lowfrequency range audio content (i.e. a subwoofer), the playback device200 may be consolidated with a playback device designed to render fullfrequency range audio content. In such a case, the full frequency rangeplayback device, when consolidated with the low frequency playbackdevice 200, may be configured to render only the mid and high frequencycomponents of audio content, while the low frequency range playbackdevice 200 renders the low frequency component of the audio content. Theconsolidated playback device may further be paired with a singleplayback device or yet another consolidated playback device.

By way of illustration, SONOS, Inc. presently offers (or has offered)for sale certain playback devices including a “PLAY:1,” “PLAY:3,”“PLAY:5,” “PLAYBAR,” “CONNECT:AMP,” “CONNECT,” and “SUB.” Any otherpast, present, and/or future playback devices may additionally oralternatively be used to implement the playback devices of exampleembodiments disclosed herein. Additionally, it is understood that aplayback device is not limited to the example illustrated in FIG. 2 orto the SONOS product offerings. For example, a playback device mayinclude a wired or wireless headphone. In another example, a playbackdevice may include or interact with a docking station for personalmobile media playback devices. In yet another example, a playback devicemay be integral to another device or component such as a television, alighting fixture, or some other device for indoor or outdoor use.

b. Example Playback Zone Configurations

Referring back to the media playback system 100 of FIG. 1, theenvironment may have one or more playback zones, each with one or moreplayback devices. The media playback system 100 may be established withone or more playback zones, after which one or more zones may be added,or removed to arrive at the example configuration shown in FIG. 1. Eachzone may be given a name according to a different room or space such asan office, bathroom, master bedroom, bedroom, kitchen, dining room,living room, and/or balcony. In one case, a single playback zone mayinclude multiple rooms or spaces. In another case, a single room orspace may include multiple playback zones.

As shown in FIG. 1, the balcony, dining room, kitchen, bathroom, office,and bedroom zones each have one playback device, while the living roomand master bedroom zones each have multiple playback devices. In theliving room zone, playback devices 104, 106, 108, and 110 may beconfigured to play audio content in synchrony as individual playbackdevices, as one or more bonded playback devices, as one or moreconsolidated playback devices, or any combination thereof. Similarly, inthe case of the master bedroom, playback devices 122 and 124 may beconfigured to play audio content in synchrony as individual playbackdevices, as a bonded playback device, or as a consolidated playbackdevice.

In one example, one or more playback zones in the environment of FIG. 1may each be playing different audio content. For instance, the user maybe grilling in the balcony zone and listening to hip hop music beingplayed by the playback device 102 while another user may be preparingfood in the kitchen zone and listening to classical music being playedby the playback device 114. In another example, a playback zone may playthe same audio content in synchrony with another playback zone. Forinstance, the user may be in the office zone where the playback device118 is playing the same rock music that is being playing by playbackdevice 102 in the balcony zone. In such a case, playback devices 102 and118 may be playing the rock music in synchrony such that the user mayseamlessly (or at least substantially seamlessly) enjoy the audiocontent that is being played out-loud while moving between differentplayback zones. Synchronization among playback zones may be achieved ina manner similar to that of synchronization among playback devices, asdescribed in previously referenced U.S. Pat. No. 8,234,395.

As suggested above, the zone configurations of the media playback system100 may be dynamically modified, and in some embodiments, the mediaplayback system 100 supports numerous configurations. For instance, if auser physically moves one or more playback devices to or from a zone,the media playback system 100 may be reconfigured to accommodate thechange(s). For instance, if the user physically moves the playbackdevice 102 from the balcony zone to the office zone, the office zone maynow include both the playback device 118 and the playback device 102.The playback device 102 may be paired or grouped with the office zoneand/or renamed if so desired via a control device such as the controldevices 126 and 128. On the other hand, if the one or more playbackdevices are moved to a particular area in the home environment that isnot already a playback zone, a new playback zone may be created for theparticular area.

Further, different playback zones of the media playback system 100 maybe dynamically combined into zone groups or split up into individualplayback zones. For instance, the dining room zone and the kitchen zone114 may be combined into a zone group for a dinner party such thatplayback devices 112 and 114 may render audio content in synchrony. Onthe other hand, the living room zone may be split into a television zoneincluding playback device 104, and a listening zone including playbackdevices 106, 108, and 110, if the user wishes to listen to music in theliving room space while another user wishes to watch television.

c. Example Control Devices

FIG. 3 shows a functional block diagram of an example control device 300that may be configured to be one or both of the control devices 126 and128 of the media playback system 100. As shown, the control device 300may include a processor 302, memory 304, a network interface 306, a userinterface 308, microphone(s) 310, and software components 312. In oneexample, the control device 300 may be a dedicated controller for themedia playback system 100. In another example, the control device 300may be a network device on which media playback system controllerapplication software may be installed, such as for example, an iPhone™,iPad™ or any other smart phone, tablet or network device (e.g., anetworked computer such as a PC or Mac™)

The processor 302 may be configured to perform functions relevant tofacilitating user access, control, and configuration of the mediaplayback system 100. The memory 304 may be data storage that can beloaded with one or more of the software components executable by theprocessor 302 to perform those functions. The memory 304 may also beconfigured to store the media playback system controller applicationsoftware and other data associated with the media playback system 100and the user.

In one example, the network interface 306 may be based on an industrystandard (e.g., infrared, radio, wired standards including IEEE 802.3,wireless standards including IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.15, 4G mobile communication standard, and so on). Thenetwork interface 306 may provide a means for the control device 300 tocommunicate with other devices in the media playback system 100. In oneexample, data and information (e.g., such as a state variable) may becommunicated between control device 300 and other devices via thenetwork interface 306. For instance, playback zone and zone groupconfigurations in the media playback system 100 may be received by thecontrol device 300 from a playback device or another network device, ortransmitted by the control device 300 to another playback device ornetwork device via the network interface 306. In some cases, the othernetwork device may be another control device.

Playback device control commands such as volume control and audioplayback control may also be communicated from the control device 300 toa playback device via the network interface 306. As suggested above,changes to configurations of the media playback system 100 may also beperformed by a user using the control device 300. The configurationchanges may include adding/removing one or more playback devices to/froma zone, adding/removing one or more zones to/from a zone group, forminga bonded or consolidated player, separating one or more playback devicesfrom a bonded or consolidated player, among others. Accordingly, thecontrol device 300 may sometimes be referred to as a controller, whetherthe control device 300 is a dedicated controller or a network device onwhich media playback system controller application software isinstalled.

Control device 300 may include microphone(s) 310. Microphone(s) 310 maybe arranged to detect sound in the environment of the control device300. Microphone(s) 310 may be any type of microphone now known or laterdeveloped such as a condenser microphone, electret condenser microphone,or a dynamic microphone. The microphone(s) may be sensitive to a portionof a frequency range. Two or more microphones 310 may be arranged tocapture location information of an audio source (e.g., voice, audiblesound) and/or to assist in filtering background noise.

The user interface 308 of the control device 300 may be configured tofacilitate user access and control of the media playback system 100, byproviding a controller interface such as the controller interface 400shown in FIG. 4. The controller interface 400 includes a playbackcontrol region 410, a playback zone region 420, a playback status region430, a playback queue region 440, and an audio content sources region450. The user interface 400 as shown is just one example of a userinterface that may be provided on a network device such as the controldevice 300 of FIG. 3 (and/or the control devices 126 and 128 of FIG. 1)and accessed by users to control a media playback system such as themedia playback system 100. Other user interfaces of varying formats,styles, and interactive sequences may alternatively be implemented onone or more network devices to provide comparable control access to amedia playback system.

The playback control region 410 may include selectable (e.g., by way oftouch or by using a cursor) icons to cause playback devices in aselected playback zone or zone group to play or pause, fast forward,rewind, skip to next, skip to previous, enter/exit shuffle mode,enter/exit repeat mode, enter/exit cross fade mode. The playback controlregion 410 may also include selectable icons to modify equalizationsettings, and playback volume, among other possibilities.

The playback zone region 420 may include representations of playbackzones within the media playback system 100. In some embodiments, thegraphical representations of playback zones may be selectable to bringup additional selectable icons to manage or configure the playback zonesin the media playback system, such as a creation of bonded zones,creation of zone groups, separation of zone groups, and renaming of zonegroups, among other possibilities.

For example, as shown, a “group” icon may be provided within each of thegraphical representations of playback zones. The “group” icon providedwithin a graphical representation of a particular zone may be selectableto bring up options to select one or more other zones in the mediaplayback system to be grouped with the particular zone. Once grouped,playback devices in the zones that have been grouped with the particularzone will be configured to play audio content in synchrony with theplayback device(s) in the particular zone. Analogously, a “group” iconmay be provided within a graphical representation of a zone group. Inthis case, the “group” icon may be selectable to bring up options todeselect one or more zones in the zone group to be removed from the zonegroup. Other interactions and implementations for grouping andungrouping zones via a user interface such as the user interface 400 arealso possible. The representations of playback zones in the playbackzone region 420 may be dynamically updated as playback zone or zonegroup configurations are modified.

The playback status region 430 may include graphical representations ofaudio content that is presently being played, previously played, orscheduled to play next in the selected playback zone or zone group. Theselected playback zone or zone group may be visually distinguished onthe user interface, such as within the playback zone region 420 and/orthe playback status region 430. The graphical representations mayinclude track title, artist name, album name, album year, track length,and other relevant information that may be useful for the user to knowwhen controlling the media playback system via the user interface 400.

The playback queue region 440 may include graphical representations ofaudio content in a playback queue associated with the selected playbackzone or zone group. In some embodiments, each playback zone or zonegroup may be associated with a playback queue containing informationcorresponding to zero or more audio items for playback by the playbackzone or zone group. For instance, each audio item in the playback queuemay comprise a uniform resource identifier (URI), a uniform resourcelocator (URL) or some other identifier that may be used by a playbackdevice in the playback zone or zone group to find and/or retrieve theaudio item from a local audio content source or a networked audiocontent source, possibly for playback by the playback device.

In one example, a playlist may be added to a playback queue, in whichcase information corresponding to each audio item in the playlist may beadded to the playback queue. In another example, audio items in aplayback queue may be saved as a playlist. In a further example, aplayback queue may be empty, or populated but “not in use” when theplayback zone or zone group is playing continuously streaming audiocontent, such as Internet radio that may continue to play untilotherwise stopped, rather than discrete audio items that have playbackdurations. In an alternative embodiment, a playback queue can includeInternet radio and/or other streaming audio content items and be “inuse” when the playback zone or zone group is playing those items. Otherexamples are also possible.

When playback zones or zone groups are “grouped” or “ungrouped,”playback queues associated with the affected playback zones or zonegroups may be cleared or re-associated. For example, if a first playbackzone including a first playback queue is grouped with a second playbackzone including a second playback queue, the established zone group mayhave an associated playback queue that is initially empty, that containsaudio items from the first playback queue (such as if the secondplayback zone was added to the first playback zone), that contains audioitems from the second playback queue (such as if the first playback zonewas added to the second playback zone), or a combination of audio itemsfrom both the first and second playback queues. Subsequently, if theestablished zone group is ungrouped, the resulting first playback zonemay be re-associated with the previous first playback queue, or beassociated with a new playback queue that is empty or contains audioitems from the playback queue associated with the established zone groupbefore the established zone group was ungrouped. Similarly, theresulting second playback zone may be re-associated with the previoussecond playback queue, or be associated with a new playback queue thatis empty, or contains audio items from the playback queue associatedwith the established zone group before the established zone group wasungrouped. Other examples are also possible.

Referring back to the user interface 400 of FIG. 4, the graphicalrepresentations of audio content in the playback queue region 440 mayinclude track titles, artist names, track lengths, and other relevantinformation associated with the audio content in the playback queue. Inone example, graphical representations of audio content may beselectable to bring up additional selectable icons to manage and/ormanipulate the playback queue and/or audio content represented in theplayback queue. For instance, a represented audio content may be removedfrom the playback queue, moved to a different position within theplayback queue, or selected to be played immediately, or after anycurrently playing audio content, among other possibilities. A playbackqueue associated with a playback zone or zone group may be stored in amemory on one or more playback devices in the playback zone or zonegroup, on a playback device that is not in the playback zone or zonegroup, and/or some other designated device.

The audio content sources region 450 may include graphicalrepresentations of selectable audio content sources from which audiocontent may be retrieved and played by the selected playback zone orzone group. Discussions pertaining to audio content sources may be foundin the following section.

d. Example Audio Content Sources

As indicated previously, one or more playback devices in a zone or zonegroup may be configured to retrieve for playback audio content (e.g.according to a corresponding URI or URL for the audio content) from avariety of available audio content sources. In one example, audiocontent may be retrieved by a playback device directly from acorresponding audio content source (e.g., a line-in connection). Inanother example, audio content may be provided to a playback device overa network via one or more other playback devices or network devices.

Example audio content sources may include a memory of one or moreplayback devices in a media playback system such as the media playbacksystem 100 of FIG. 1, local music libraries on one or more networkdevices (such as a control device, a network-enabled personal computer,or a networked-attached storage (NAS), for example), streaming audioservices providing audio content via the Internet (e.g., the cloud), oraudio sources connected to the media playback system via a line-in inputconnection on a playback device or network devise, among otherpossibilities.

In some embodiments, audio content sources may be regularly added orremoved from a media playback system such as the media playback system100 of FIG. 1. In one example, an indexing of audio items may beperformed whenever one or more audio content sources are added, removedor updated. Indexing of audio items may involve scanning foridentifiable audio items in all folders/directory shared over a networkaccessible by playback devices in the media playback system, andgenerating or updating an audio content database containing metadata(e.g., title, artist, album, track length, among others) and otherassociated information, such as a URI or URL for each identifiable audioitem found. Other examples for managing and maintaining audio contentsources may also be possible.

The above discussions relating to playback devices, controller devices,playback zone configurations, and media content sources provide onlysome examples of operating environments within which functions andmethods described below may be implemented. Other operating environmentsand configurations of media playback systems, playback devices, andnetwork devices not explicitly described herein may also be applicableand suitable for implementation of the functions and methods.

e. Example Plurality of Networked Devices

FIG. 5 shows an example plurality of devices 500 that may be configuredto provide an audio playback experience based on voice control. Onehaving ordinary skill in the art will appreciate that the devices shownin FIG. 5 are for illustrative purposes only, and variations includingdifferent and/or additional devices may be possible. As shown, theplurality of devices 500 includes computing devices 504, 506, and 508;network microphone devices (NMDs) 512, 514, and 516; playback devices(PBDs) 532, 534, 536, and 538; and a controller device (CR) 522.

Each of the plurality of devices 500 may be network-capable devices thatcan establish communication with one or more other devices in theplurality of devices according to one or more network protocols, such asNFC, Bluetooth, Ethernet, and IEEE 802.11, among other examples, overone or more types of networks, such as wide area networks (WAN), localarea networks (LAN), and personal area networks (PAN), among otherpossibilities.

As shown, the computing devices 504, 506, and 508 may be part of a cloudnetwork 502. The cloud network 502 may include additional computingdevices. In one example, the computing devices 504, 506, and 508 may bedifferent servers. In another example, two or more of the computingdevices 504, 506, and 508 may be modules of a single server.Analogously, each of the computing device 504, 506, and 508 may includeone or more modules or servers. For ease of illustration purposesherein, each of the computing devices 504, 506, and 508 may beconfigured to perform particular functions within the cloud network 502.For instance, computing device 508 may be a source of audio content fora streaming music service.

As shown, the computing device 504 may be configured to interface withNMDs 512, 514, and 516 via communication path 542. NMDs 512, 514, and516 may be components of one or more “Smart Home” systems. In one case,NMDs 512, 514, and 516 may be physically distributed throughout ahousehold, similar to the distribution of devices shown in FIG. 1. Inanother case, two or more of the NMDs 512, 514, and 516 may bephysically positioned within relative close proximity of one another.Communication path 542 may comprise one or more types of networks, suchas a WAN including the Internet, LAN, and/or PAN, among otherpossibilities.

In one example, one or more of the NMDs 512, 514, and 516 may be devicesconfigured primarily for audio detection. In another example, one ormore of the NMDs 512, 514, and 516 may be components of devices havingvarious primary utilities. For instance, as discussed above inconnection to FIGS. 2 and 3, one or more of NMDs 512, 514, and 516 maybe the microphone(s) 220 of playback device 200 or the microphone(s) 310of network device 300. Further, in some cases, one or more of NMDs 512,514, and 516 may be the playback device 200 or network device 300. In anexample, one or more of NMDs 512, 514, and/or 516 may include multiplemicrophones arranged in a microphone array.

As shown, the computing device 506 may be configured to interface withCR 522 and PBDs 532, 534, 536, and 538 via communication path 544. Inone example, CR 522 may be a network device such as the network device200 of FIG. 2. Accordingly, CR 522 may be configured to provide thecontroller interface 400 of FIG. 4. Similarly, PBDs 532, 534, 536, and538 may be playback devices such as the playback device 300 of FIG. 3.As such, PBDs 532, 534, 536, and 538 may be physically distributedthroughout a household as shown in FIG. 1. For illustration purposes,PBDs 536 and 538 may be part of a bonded zone 530, while PBDs 532 and534 may be part of their own respective zones. As described above, thePBDs 532, 534, 536, and 538 may be dynamically bonded, grouped,unbonded, and ungrouped. Communication path 544 may comprise one or moretypes of networks, such as a WAN including the Internet, LAN, and/orPAN, among other possibilities.

In one example, as with NMDs 512, 514, and 516, CR522 and PBDs 532, 534,536, and 538 may also be components of one or more “Smart Home” systems.In one case, PBDs 532, 534, 536, and 538 may be distributed throughoutthe same household as the NMDs 512, 514, and 516. Further, as suggestedabove, one or more of PBDs 532, 534, 536, and 538 may be one or more ofNMDs 512, 514, and 516.

The NMDs 512, 514, and 516 may be part of a local area network, and thecommunication path 542 may include an access point that links the localarea network of the NMDs 512, 514, and 516 to the computing device 504over a WAN (communication path not shown). Likewise, each of the NMDs512, 514, and 516 may communicate with each other via such an accesspoint.

Similarly, CR 522 and PBDs 532, 534, 536, and 538 may be part of a localarea network and/or a local playback network as discussed in previoussections, and the communication path 544 may include an access pointthat links the local area network and/or local playback network of CR522 and PBDs 532, 534, 536, and 538 to the computing device 506 over aWAN. As such, each of the CR 522 and PBDs 532, 534, 536, and 538 mayalso communicate with each over such an access point.

In one example, communication paths 542 and 544 may comprise the sameaccess point. In an example, each of the NMDs 512, 514, and 516, CR 522,and PBDs 532, 534, 536, and 538 may access the cloud network 502 via thesame access point for a household.

As shown in FIG. 5, each of the NMDs 512, 514, and 516, CR 522, and PBDs532, 534, 536, and 538 may also directly communicate with one or more ofthe other devices via communication means 546. Communication means 546as described herein may involve one or more forms of communicationbetween the devices, according to one or more network protocols, overone or more types of networks, and/or may involve communication via oneor more other network devices. For instance, communication means 546 mayinclude one or more of for example, Bluetooth™ (IEEE 802.15), NFC,Wireless direct, and/or Proprietary wireless, among other possibilities.

In one example, CR 522 may communicate with NMD 512 over Bluetooth™, andcommunicate with PBD 534 over another local area network. In anotherexample, NMD 514 may communicate with CR 522 over another local areanetwork, and communicate with PBD 536 over Bluetooth. In a furtherexample, each of the PBDs 532, 534, 536, and 538 may communicate witheach other according to a spanning tree protocol over a local playbacknetwork, while each communicating with CR 522 over a local area network,different from the local playback network. Other examples are alsopossible.

In some cases, communication means between the NMDs 512, 514, and 516,CR 522, and PBDs 532, 534, 536, and 538 may change depending on types ofcommunication between the devices, network conditions, and/or latencydemands. For instance, communication means 546 may be used when NMD 516is first introduced to the household with the PBDs 532, 534, 536, and538. In one case, the NMD 516 may transmit identification informationcorresponding to the NMD 516 to PBD 538 via NFC, and PBD 538 may inresponse, transmit local area network information to NMD 516 via NFC (orsome other form of communication). However, once NMD 516 has beenconfigured within the household, communication means between NMD 516 andPBD 538 may change. For instance, NMD 516 may subsequently communicatewith PBD 538 via communication path 542, the cloud network 502, andcommunication path 544. In another example, the NMDs and PBDs may nevercommunicate via local communications means 546. In a further example,the NMDs and PBDs may communicate primarily via local communicationsmeans 546. Other examples are also possible.

In an illustrative example, NMDs 512, 514, and 516 may be configured toreceive voice inputs to control PBDs 532, 534, 536, and 538. Theavailable control commands may include any media playback systemcontrols previously discussed, such as playback volume control, playbacktransport controls, music source selection, and grouping, among otherpossibilities. In one instance, NMD 512 may receive a voice input tocontrol one or more of the PBDs 532, 534, 536, and 538. In response toreceiving the voice input, NMD 512 may transmit via communication path542, the voice input to computing device 504 for processing. In oneexample, the computing device 504 may convert the voice input to anequivalent text command, and parse the text command to identify acommand. Computing device 504 may then subsequently transmit the textcommand to the computing device 506. In another example, the computingdevice 504 may convert the voice input to an equivalent text command,and then subsequently transmit the text command to the computing device506. The computing device 506 may then parse the text command toidentify one or more playback commands.

For instance, if the text command is “Play ‘Track 1’ by ‘Artist 1’ from‘Streaming Service 1’ in ‘Zone 1’,” The computing device 506 mayidentify (i) a URL for “Track 1” by “Artist 1” available from “StreamingService 1,” and (ii) at least one playback device in “Zone 1.” In thisexample, the URL for “Track 1” by “Artist 1” from “Streaming Service 1”may be a URL pointing to computing device 508, and “Zone 1” may be thebonded zone 530. As such, upon identifying the URL and one or both ofPBDs 536 and 538, the computing device 506 may transmit viacommunication path 544 to one or both of PBDs 536 and 538, theidentified URL for playback. One or both of PBDs 536 and 538 mayresponsively retrieve audio content from the computing device 508according to the received URL, and begin playing “Track 1” by “Artist 1”from “Streaming Service 1.”

One having ordinary skill in the art will appreciate that the above isjust one illustrative example, and that other implementations are alsopossible. In one case, operations performed by one or more of theplurality of devices 500, as described above, may be performed by one ormore other devices in the plurality of device 500. For instance, theconversion from voice input to the text command may be alternatively,partially, or wholly performed by another device or devices, such as NMD512, computing device 506, PBD 536, and/or PBD 538. Analogously, theidentification of the URL may be alternatively, partially, or whollyperformed by another device or devices, such as NMD 512, computingdevice 504, PBD 536, and/or PBD 538.

f. Example Network Microphone Device

FIG. 6 shows a function block diagram of an example network microphonedevice 600 that may be configured to be one or more of NMDs 512, 514,and 516 of FIG. 5. As shown, the network microphone device 600 includesa processor 602, memory 604, a microphone array 606, a network interface608, a user interface 610, software components 612, and speaker(s) 614.One having ordinary skill in the art will appreciate that other networkmicrophone device configurations and arrangements are also possible. Forinstance, network microphone devices may alternatively exclude thespeaker(s) 614 or have a single microphone instead of microphone array606.

The processor 602 may include one or more processors and/or controllers,which may take the form of a general or special-purpose processor orcontroller. For instance, the processing unit 602 may includemicroprocessors, microcontrollers, application-specific integratedcircuits, digital signal processors, and the like. The memory 604 may bedata storage that can be loaded with one or more of the softwarecomponents executable by the processor 602 to perform those functions.Accordingly, memory 604 may comprise one or more non-transitorycomputer-readable storage mediums, examples of which may includevolatile storage mediums such as random access memory, registers, cache,etc. and non-volatile storage mediums such as read-only memory, ahard-disk drive, a solid-state drive, flash memory, and/or anoptical-storage device, among other possibilities.

The microphone array 606 may be a plurality of microphones arranged todetect sound in the environment of the network microphone device 600.Microphone array 606 may include any type of microphone now known orlater developed such as a condenser microphone, electret condensermicrophone, or a dynamic microphone, among other possibilities. In oneexample, the microphone array may be arranged to detect audio from oneor more directions relative to the network microphone device. Themicrophone array 606 may be sensitive to a portion of a frequency range.In one example, a first subset of the microphone array 606 may besensitive to a first frequency range, while a second subset of themicrophone array may be sensitive to a second frequency range. Themicrophone array 606 may further be arranged to capture locationinformation of an audio source (e.g., voice, audible sound) and/or toassist in filtering background noise. Notably, in some embodiments themicrophone array may consist of only a single microphone, rather than aplurality of microphones.

The network interface 608 may be configured to facilitate wirelessand/or wired communication between various network devices, such as, inreference to FIG. 5, CR 522, PBDs 532- 538, computing device 504-508 incloud network 502, and other network microphone devices, among otherpossibilities. As such, network interface 608 may take any suitable formfor carrying out these functions, examples of which may include anEthernet interface, a serial bus interface (e.g., FireWire, USB 2.0,etc.), a chipset and antenna adapted to facilitate wirelesscommunication, and/or any other interface that provides for wired and/orwireless communication. In one example, the network interface 608 may bebased on an industry standard (e.g., infrared, radio, wired standardsincluding IEEE 802.3, wireless standards including IEEE 802.11a,802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4G mobile communicationstandard, and so on).

The user interface 610 of the network microphone device 600 may beconfigured to facilitate user interactions with the network microphonedevice. In one example, the user interface 608 may include one or moreof physical buttons, graphical interfaces provided on touch sensitivescreen(s) and/or surface(s), among other possibilities, for a user todirectly provide input to the network microphone device 600. The userinterface 610 may further include one or more of lights and thespeaker(s) 614 to provide visual and/or audio feedback to a user. In oneexample, the network microphone device 600 may further be configured toplayback audio content via the speaker(s) 614.

III. Example Systems

Embodiments described herein involve calibrating (e.g., adjusting)acoustics of an audio playback device for an environment, e.g., room, inwhich the audio playback device is located based on an estimatedfrequency response of the audio playback device.

FIG. 7 illustrates such an example environment 700 in which the audioplayback device may be calibrated in accordance with disclosedembodiments. The example environment may be, for example, a living roomor bedroom of a home. The environment 700 may have an audio playbackdevice 702 capable of outputting audio content in one or more directionsvia one or more speakers. In embodiments, the audio content may not belimited to one or more predetermined test tones at one or morefrequencies, but may include spectral content which may take the form ofone or more of digital or analog music, television audio, and radio. Thespectral content may be provided by the computing device 508 via thecloud network 502. For example, the computing device may be a musicservice provider such as Spotify, Amazon Music, Pandora, among others,and the cloud network may be a wide area network (WAN) such as theInternet. The audio content may have frequencies substantially coveringa renderable frequency range of the playback device, a detectablefrequency range of the microphone, and/or an audible frequency range foran average human.

The audio playback device 702 may have one or more microphones 704 forrecording an audio signal output by the audio playback device. The oneor more microphones 704 may be proximate to the audio playback device.For example, the microphone may be co-located physically on or in theplayback device or wired or wirelessly connected to the audio playbackdevice. The audio signal output by the audio playback device recorded atthe audio playback device may be used to determine an estimatedfrequency response of the audio playback device (i.e., a self-response).The self-response may be used to calibrate the audio playback device.

The room 700 may also have one or more network devices 706. The networkdevice 706 may be a controller device, NMD, or another audio playbackdevice. The network device 706 may have one or more microphones 708 forrecording an audio signal output by the audio playback device 702 at aspatial location in the environment 700 different from the spatiallocation of the audio playback device 702. The different location mightbe in front of the audio playback device 702, behind the audio playbackdevice 702, or adjacent to the audio playback device 702. The audiosignal output by the audio playback device recorded at the networkdevice may be used to determine an estimated frequency response of theaudio playback device (i.e., a test response). The test response may beused to calibrate the audio playback device.

In some embodiments, the network device 706 may also be physicallymovable. In this regard, the microphone of the network device 706 mayrecord the audio signal output by the audio playback device 702 at oneor more spatial locations in the environment. For example, thecontroller device may be physically moved to one or more spatiallocations in the environment and the microphone of the controller devicemay record the audio signal output by the audio playback device 702.Alternatively, a wired or wireless microphone of the audio playbackdevice 702 may be moved to the different spatial locations to record theaudio signal output by the audio playback device 702 in a manner similarto that of the controller device. Still alternatively, an NMD may bemoved to various spatial locations in the environment to record theaudio signal output by the audio playback device 702. Additionally, oralternatively, a plurality of NMDs fixed at various locations in theroom may be used to record the audio signal output by the audio playbackdevice 702 at different spatial locations in the room rather thanphysically moving the NMD in the environment 700. The recorded audiosignal output by the audio playback device may be used to determine anestimated frequency response of the audio playback device. The estimatedfrequency response may be used to calibrate (e.g., adjust) acoustics ofthe audio playback device.

FIG. 8 shows an example flow diagram of functions associated withcalibrating a playback device in accordance with the disclosedembodiments. Methods and the other process disclosed herein may includeone or more operations, functions, or actions. Although the blocks areillustrated in sequential order, these blocks may also be performed inparallel, and/or in a different order than those described herein. Also,the various blocks may be combined into fewer blocks, divided intoadditional blocks, and/or removed based upon the desired implementation.

In addition, for the methods and other processes and methods disclosedherein, the flowchart shows functionality and operation of one possibleimplementation of present embodiments. In this regard, each block mayrepresent a module, a segment, or a portion of program code, whichincludes one or more instructions executable by a processor forimplementing specific logical functions or steps in the process. Theprogram code may be stored on any type of computer readable medium, forexample, such as a storage device including a disk or hard drive. Thecomputer readable medium may include non-transitory computer readablemedium, for example, such as computer-readable media that stores datafor short periods of time like register memory, processor cache andRandom Access Memory (RAM). The computer readable medium may alsoinclude non-transitory media, such as secondary or persistent long termstorage, like read only memory (ROM), optical or magnetic disks,compact-disc read only memory (CD-ROM), for example. The computerreadable media may also be any other volatile or non-volatile storagesystems. The computer readable medium may be considered a computerreadable storage medium, for example, or a tangible storage device. Inaddition, each block in the figures may represent circuitry that iswired to perform the specific logical functions in the process.

In one example, the disclosed functions for the calibration may be atleast partially performed by the audio playback device 200. In anotherexample, the disclosed functions for the calibration may be at leastpartially performed by the computing device 504-508. In yet anotherexample, functions for the calibration may be at least partiallyperformed by the controller device 300. In another example, functionsfor the calibration may be at least partially performed by an NMD512-516. Other arrangements are also possible.

Briefly, at 802, a determination is made that the audio playback deviceis in a calibration period. At 804, a first stream of audio is received,e.g., via a wide area network. The first stream of audio comprisessource audio content to be played back by the audio playback device. At806, a second stream of audio is received. The second stream of audiocomprises a recording of an audio signal output by the audio playbackdevice based on the audio playback device playing the source audiocontent. At 808, an estimated frequency response of an audio playbackdevice is calculated based on the received first stream of audio and thereceived second stream of audio. At 810, acoustics of the audio playbackdevice is adjusted based on the estimated frequency response. Thefunctions of the example process shown in FIG. 8 will now be describedin further detail.

Starting at 802, a determination is made that the audio playback deviceis in a calibration period. The calibration period may be a time whenthe audio content output by the playback device may be calibrated. Thecalibration period may take the form of a discrete or a continuouscalibration period.

The discrete calibration period may be a calibration which occurs when acondition is satisfied. For example, the condition may be that a user issetting up or configuring the audio playback device for a first time orafter being reset. Alternatively, the condition may be a determinationthat a calibration has not been performed before on the audio playbackdevice. Still alternatively, the condition may be a determination that aprevious calibration is invalid or a previous calibration attempt on theplayback device was unsuccessful. For example, the condition may be atime elapsed since a last calibration of the audio playback device orafter a “break in” period of the audio playback device. The “break in”period may be the period of time until acoustic components of a speakersuch as the cones, diaphragms, and/or drivers move freely and experiencea full range of motion. The condition associated with calibration periodmay be met once the “break in” period is complete.

Movement and/or change in orientation of the audio playback device mayalso be a condition for triggering calibration. Movement may be a changein spatial location of the audio playback device. Change in orientationmay be a change in angular position of the audio playback device. Forexample, the audio playback device may be not longer resting parallelwith a supporting surface such as a shelf but rather angled upwards ordownwards. The change in orientation may result in the audio playbackdevice outputting audio on one direction versus another direction.Additionally, or alternatively, the change in orientation may be arotation of the audio playback device. For example, the audio playbackdevice may be rotated by 90 degrees so that the audio playback devicerests on one of its sides rather than another of its sides. Movementand/or change in orientation of the device may be suggestive of a changein an acoustic response of the audio playback device and a need forcalibration.

In one example, the audio playback device may be equipped with a sensorsuch as an accelerometer, global positioning system (GPS), and/orgyroscope for detecting movement and/or a change in orientation of theaudio playback device. The sensor may output a signal when the audioplayback device moves or changes orientation. In another example, theaudio playback device may have an IP address associated with its currentlocation. If the audio playback device is disconnected from thecommunication means 546 and then reconnected, e.g., it is moved from abedroom to a living room, the audio playback device may be assigned anew IP address. A change in the IP address may indicate that the audioplayback device has moved. In still another example, a change in a labelof the audio playback device may indicate that the audio playback devicehas moved. The audio playback device may be labeled such as “BedroomDevice” or “Living Room Device” to facilitate identification of theaudio playback device by a user. A change in the label of the audioplayback device, e.g., from “Bedroom Device” to “Living Room Device” maybe indicative of the audio playback device being moved.

In some configurations, a change in bonding of the audio playback devicemay be a condition for triggering calibration. The audio playback devicemay be bonded to one or more other playback devices to form a bondedzone. The bonded zone may represent one or more audio playback devicesplaying audio in synchrony. Calibration may be triggered if the audioplayback device is bonded with another one or more playback devices andin the new bond the audio playback device changes its equalization,spatial, and/or temporal response. The equalization response may defineadjustments to frequencies output by the playback device. The spatialresponse may define a direction in which the audio content is directed,e.g., using beamforming techniques. The temporal response may define aphase of the audio played by the playback device.

The audio playback device may refer to a state variable in determiningwhether to trigger the calibration. The state variable may define astate of the audio playback device. For example, the state variable mayindicate a position/orientation of the device. A change inposition/orientation indicated by the state variable suggests that theplayback device moved. As another example, the state variable mayindicate which devices a playback device is bonded to. A change in thebonded device(s) may indicate a change in bonding. As yet anotherexample, the state variable may indicate whether the playback device hasbeen set up, calibrated previously, or when it was last calibrated. Thestate variable may indicate other states of the audio playback device aswell. The state variable may be maintained at the audio playback device,the controller device, and/or computing device and exchanged among audioplayback devices via the communications means 546.

The continuous calibration process may be a calibration of the audioplayback device which continues so long as the playback device playsaudio content. The continuous calibration process may normally run as abackground process while the audio playback device plays back audiocontent.

The continuous calibration may be suspended in some instances. In oneexample, the continuous calibration may be suspended whennon-linearities are introduced during signal processing of the sourceaudio content. Such non-linearities could occur at upper and lowervolume range extremes. The non-linearities may degrade a signal to noiseratio of the audio signal output by the audio playback device. In thisregard, non-linearities in processing the source audio content maydetermine whether continuous calibration is performed.

As another example, a magnitude of an audio signal output by the audioplayback device may cause the continuous calibration to be suspended. Avolume setting of an audio playback device may be compared to athreshold level. If the volume setting of the audio playback device isbelow the threshold level, then a signal to noise ratio of the audiosignal output by the audio playback device may be too low to perform thecontinuous calibration. The volume setting that is compared may be theactual volume setting or a filtered volume setting such as an averagevolume setting. Additionally, or alternatively, if a sound level of thesource audio content is below a threshold level, then a signal to noiseratio of the audio signal output by the audio playback device may be toolow to perform the continuous calibration. A magnitude of digitalsamples of the source audio content may define the sound level of thesource audio content. The sound level that is compared to the thresholdmay be the actual sound level or a filtered sound level such as anaverage sound level.

The source audio content may span a frequency range from a low frequencyto a high frequency. For example, the frequency range may be one or morefrequencies between 20 Hz and 20,000 Hz which is the typical audiofrequency range for music. The source audio content may comprise digitalsamples of audio. A frequency and magnitude may be associated with oneor more digital samples.

A spectral coverage of the source audio content may determine whetherthe continuous calibration is suspended. Digital samples of the sourceaudio content may in a time domain. The digital samples of the sourceaudio content may be transformed from the time domain into a frequencydomain representation by a transform function such as a Fast FourierTransform (FFT). The frequency domain representation of the source audiocontent may represent the spectral coverage of the source audio content.

The spectral coverage of the source audio content may be subdivided intofrequency bins. FIG. 9 illustrates an example of frequency binning. InFIG. 9, the frequency domain representation of the source audio contentmay be subdivided in frequency bins, shown as exemplary frequency binsFreq. 1 to Freq. 8. The frequency bins may be arranged along an X axis900 and represent a subset of uniform or non-uniform frequency rangesbetween a low frequency, e.g., 20 Hz, and a high frequency, e.g., 20,000Hz. A magnitude of each of the frequency bins may then represent anamount of spectral content within the frequency bin as shown by the Yaxis 902. The magnitude may be an average of the magnitudes in thefrequency bin, a maximum magnitude in the frequency bin, or some othermeasure.

If a magnitude of the spectral content in one or more frequency bins isless than a threshold level, then continuous calibration (and perhapsalso discrete calibration) may not be performed. Referring to FIG. 9,the magnitude of the frequency content in Freq. 3 and Freq. 6 bins maybe less than the threshold 902. As a result, the continuous calibrationmay not be performed.

In another example, a continuous calibration may be performed eventhough a magnitude of the spectral content in one or more frequency binsis less than a threshold level. For example, the frequency bins withinsufficient spectral coverage may be “logged” and filled in withspectral content when the source audio content has sufficient spectralcontent in those frequency bins. In the meantime, other sufficientspectral content (e.g., covering a same frequency range of the frequencybin) may be used during the calibration. The other sufficient spectralcontent may be based on source audio content previously played back bythe audio playback device or predetermined spectral content. As anotherexample, the spectral content in those frequency bins with insufficientspectral content may be estimated through a filtering process such asinterpolation. Spectral content in adjacent frequency bins may beinterpolated to fill in the frequency bins with insufficient spectralcontent. Other arrangements are also possible.

At 804, a first stream of audio may be received, e.g., via a wide areanetwork. The first stream may comprise source audio content to be playedback by the audio playback device. Further, the stream may be segmentedinto one or more chunks of data. For example, the chunks may take theform of packets of digital samples of audio content. These chunks ofdata may be stored on the audio playback device being calibrated and/orstored on a computing device associated with the calibration of theaudio playback device.

This source content may be received via an audio pipeline. FIG. 10 showssuch an exemplary audio pipeline 1000. The audio pipeline 1000 mayinclude a source 1002, a signal processor 1004, a digital to analogconverter 1006, and a speaker 1008 coupled via one or more communicationlinks.

The audio pipeline 1000 may reside on an audio playback device, thecontroller device, computing device, NMD, or a combination thereof Inthe case of the audio pipeline residing on an audio playback device, thecommunication links may take the form of traces on a printed circuitboard. In the case of the audio pipeline residing on the combinationthereof, the communication links may take the form of a wired orwireless network such as an Ethernet or WiFi network.

The source 1002 may be a storage device such as memory or a hard drivewhich stores source audio content. Alternatively, the source 1002 may bea computing device such as a music service provider which stores andprovides the source audio content to the audio playback device. Thesource audio content may take the form of an audio file of digitalsamples defining audio content in a time domain.

The signal processor 1004 may apply one or more filtering algorithms tothe source audio content prior to the audio playback device outputtingan audio signal. The filtering algorithms may vary based one or more ofa volume setting of the audio playback device, previous calibration ofthe playback device, device orientation, content type, etc. Further, thesignal processor 1004 include one or more of a sample rate converter,bit depth converter, and channel up/down mixer. The sample rateconverter may change a sample rate of the source audio content. Thesample rate may define a number of samples representing the source audiocontent per unit time. The bit depth converter may change a bit depth ofthe source audio content signal. The bit depth may be a number of bitsused to represent a digital sample. The channel up/down mixer may mixsource audio content from different channels such as a left and rightchannel of stereo sound. The signal processor 1004 may perform otherfunctions as well.

In embodiments, the signal processor 1004 may process the source audiocontent in a digital domain and output a processed digital signal. Thedigital to analog converter 1006 may convert the digital signal of thesignal processor 1004 to an analog signal. The analog signal may beoutput to the speaker 1008 which converts the analog signal to audibleaudio.

The source audio content that is used in calibration may be received atthe tap 1010 or tap 1012 of FIG. 10. In the case that the source audiocontent is received at 1010, then processing that would otherwise beapplied by the signal processor 1004 may need to be applied to thesource audio content prior to calculating the estimated frequencyresponse at 808 which is discussed below.

At 806, a second stream of audio may be received. The second stream maybe a recorded audio signal output by the audio playback device based onthe audio playback device playing the source audio content. The audiosignal may be a time domain representation of the audio content outputby the playback device. The stream may be segmented into one or morechunks of data, e.g., packets. The received audio signal may be storedon the audio playback device or passed to another network device, suchas a computing device, another audio playback device, control device orNMD.

The audio playback device that is being calibrated may record the audiosignal. The audio signal may be recorded via one or more microphonesco-located on the audio playback device being calibrated. Alternatively,the audio signal may be recorded via one or more microphones in aspatially different location from the audio playback device beingcalibrated. For example, another audio playback device may record thisaudio signal, a network device may receive this audio signal, and/or aNMD may record this audio signal.

At 808, the received first stream of audio, e.g., source audio content,and the received second stream of audio, e.g., recorded audio signal,may be processed to calculate an estimated frequency response of theaudio playback device. The processing may be performed by one or more ofa computing device, audio playback device being calibrated, anotheraudio playback device, NMD, and/or controller device. The processing maybe performed in real time as chunks of source audio content is receivedand audio signal output by the audio playback device is recorded. Thisreal-time processing may be performed when there is sufficientprocessing power available. Alternatively, when limited processing poweris available, processing may be performed after a “sufficient” amount ofchunks of source audio content and audio signal is recorded. Sufficientmay be dependent on implementation but may be when a certain number ofchunks or packets associated with the source audio content and/or therecorded audio signal output by the audio playback device is received.For example, sufficient may be the source audio content received/audiooutput signal recorded in a one second interval, a one-minute interval,or some time interval in between. Alternatively, sufficient may be acertain number of packets. Other arrangements are also possible.

Chunks of the source audio content and the audio signal output by theaudio playback device may be in a time domain. The chunks in the timedomain may be transformed into a frequency domain representation using atransformation technique such as the Fast Fourier Transform (FFT). Thefrequency domain representation identifies spectral content of thechunks. In some embodiments, spectral content may be added to thespectral content of the chunks of the source audio content and/or theaudio signal output by the audio playback device. Consistent with thediscussion above with respect to FIG. 9, the spectral content added maybe based on spectral content already in one or more frequency binsassociated the frequency domain representation. The spectral contentadded may be source audio content previously played back by the audioplayback device, the audio signal output by the audio playbackpreviously, and/or predetermined spectral content. Additionally, oralternatively, the spectral content added may be based on a filteringprocess such as interpolation being performed on the spectral contentalready in one or more bins. Other arrangements are also possible.

The source audio content and the audio signal output may be eachrepresented as a vector of data with a magnitude and phase in thefrequency domain. A transfer function may be a difference between thesource audio content vector (S) and the output audio signal vector (M).

This transfer function may be calculated based on an adaptive echocancellation algorithm. The characteristic equation for adaptive echocancellation may be represented as:

M=[S*H+X]  (1)

where M is a complex vector in the frequency domain representing amagnitude and phase of the recorded audio signal output by the audioplayback device;

S is a complex vector in the frequency domain representing a magnitudeand phase of the source audio content vector;

H is a complex transfer function in the frequency domain representing adifference between the S and M in the absence of any recordedinterference in M; and

X represents the recorded interference, e.g., static noise (e.g., buzz)or background noise (e.g., speech) in M. If there is no recordedinterference in M, then M=S*X and X=0.

A real part of H, e.g., a magnitude component of the S to M transferfunction may be calculated as:

magH_(n)=(magS_(n) 31 magM_(n))a _(n)+(1−a _(n))(magH_(n-1))   (2)

where a is a signal to interference ratio, e.g., the signal may be S andthe interference may be the recorded interference X. a may berepresented as a function of a logarithmic value normalized between 0and 1;

magS_(n) is a magnitude component vector of the source audio contentvector;

magM_(n) is a magnitude component vector of the recorded output audiosignal vector; and

-   -   n is an iteration.

With each iteration, a magnitude component vector of the output audiosignal vector magM, a magnitude component vector of the source audiocontent magS, and the magnitude component of the S to M transferfunction magH from one iteration is used to calculate the magnitudecomponent of the S to M transfer function for the next iteration.

The following calculation may be performed for each iteration:

magM_(n)−magS_(n)*magH_(n)   (3)

where magM_(n) is a magnitude component vector of the recorded outputaudio signal vector;

magS_(n) is a magnitude component vector of the source audio contentvector;

magH_(n) is a magnitude component of the S to M transfer function.

The transfer function may converge when a result of equation (3) issubstantially zero. Alternatively, for each iteration n an average maybe calculated based on a result of equation (3) for the currentiteration and results of equation (3) for one or more past iterations.The transfer function may converge when a slope of averages based onequation (3) over a plurality of iterations is substantially zero.Various well known convergence algorithms such as L2 norm may alsoindicate convergence.

An estimated frequency response of the audio playback device may bedetermined based on magH and a self-response of the audio playbackdevice in an anechoic chamber. The self-response of the audio playbackdevice in an anechoic chamber may involve playing audio by the audioplayback device in an anechoic chamber and recording the audio signaloutput by the audio playback device at the audio playback device. Thisself-response may be determined during a testing phase of the audioplayback device (either of the audio playback device itself or anotheraudio playback device which is similar to the audio playback device) andstored in the computing device, controller device, NMD, or the audioplayback device itself In some instances, the estimated frequencyresponse may be a difference between magH and the self-response of theaudio playback device in the anechoic chamber.

In one example, the network device which records the audio signal outputby the audio playback device may be a controller device, NMD, or anotherplayback device at a spatial location different from where the audioplayback device is located. In this regard, the estimated frequencyresponse may be a test response, e.g., a response of the audio playbackdevice at the spatial location of the network device. In anotherexample, the audio playback device may play back the source audiocontent and record the audio signal output by the playback device viaone or more microphones proximate to the audio playback device. Forexample, the microphone may be co-located physically on or in theplayback device or wired or wirelessly connected to the audio playbackdevice. The estimated frequency response may be a self-response, i.e., aresponse of the audio playback device determined based on receiving theaudio signal output by the audio playback device at the one or moremicrophones of the audio playback device.

Further, the estimated frequency response may be an absolute response ofthe audio playback device or a filtered response of the audio playbackdevice. The absolute response may be the estimated frequency response ofthe audio playback device based on the source audio content and recordedaudio signal output received over a given period of time. The filteredresponse may be an average of estimated frequency responses calculatedat different periods of time. In some examples, the estimated frequencyresponse may also be weighted with higher weightings applied toestimated frequency responses which may have been determined morerecently and lower weightings applied to estimated frequency responseswhich may have been determined less recently. The filtered response maycontinue to be updated as estimated responses are determined fordifferent periods of time (i.e., a moving average). Additionally, if thenetwork device is spatially moving, the filtered response may also be aspace averaged response across the portion of space covered by thenetwork device during the period of time.

In the case of discrete calibration, processing associated withfrequency response estimation may stop once the estimated frequencyresponse is determined. In the case of a continuous calibration,processing may continue with calculation of updated frequency responseestimation as source audio content is received and audio signal outputby the audio playback device is recorded.

In either case, at 810, the estimated frequency response may be used toadjust (e.g., calibrate) acoustics of the audio playback device. Theadjustment may be performed by one or more of the audio playback devicebeing calibrated, another audio playback device, an NMD, a controllerdevice, and/or a computing device such as a server.

The calibration may be performed in a plurality of ways. In one example,an audio processing algorithm may be selected from a database of audioprocessing algorithms based on the estimated frequency response of theaudio playback device. In another example, the audio processingalgorithm may be dynamically computed based on the estimated frequencyresponse of the audio playback device. The audio processing algorithmmay take the form of a filter or equalization setting which is used toadjust acoustics of the audio playback device for the environment. Thisfilter or equalization may be applied to the audio content played by theplayback device until such time that the filter or equalization ischanged or is no longer valid.

The filter or equalization setting may be applied by the audio playbackdevice. Alternatively, the filter or equalization may be applied byanother audio playback device, the server, and/or the controller devicewhich then provides the processed audio content to the audio playbackdevice for playback via a communication network. Other arrangements arealso possible.

In some situations, the audio playback device cannot be calibratedbecause the transfer function H does not converge. The audio playbackdevice may have a plurality of microphones. Each of the microphones mayrecord source audio content. In this regard, a transfer function H maybe calculated for each microphone of a plurality of microphones in aplayback device. Failure to converge may be indicated by a lack ofcorrelation between a transfer function H associated with one microphoneof the audio playback device and transfer functions H associated withone or more of the other microphones of the audio playback device. Inthis situation, the lack of correlation may indicate that the playbackdevice should be moved. Then, the calibration process can be startedagain.

FIG. 11 illustrates an exemplary user interface 1100 in the event thatthe audio playback device is unable to be calibrated. A user may berequested to select whether to perform the calibration again. If theuser selects to calibrate again, a user interface 1102 may be presentedthat requests the user to take some action. The action illustrated inFIG. 11 is for the user to move the audio playback device and confirmthe audio playback device has moved to complete the calibration.

Alternatives to moving the playback device when the calibration is notsuccessful. may include, but is not limited to those described in U.S.patent application Ser. No. 14/864,393, entitled “FacilitatingCalibration of an Audio Playback Device” and/or U.S. patent applicationSer. No. 15/096,827, entitled “Calibration of Audio Playback Devices”,the contents each of which is herein incorporated by reference in itsentirety. Further, in other embodiments, the user interface may providean indication that calibration cannot be performed.

In other situations, the audio playback device cannot be calibrated atall. The audio playback device may be impaired, e.g., a microphone orspeaker of the audio playback device may be broken. Impairments in theaudio playback device may be detected based on analyzing the transferfunction H determined for the audio playback device. The transferfunction H may define a response for a range of frequencies. If thetransfer function H for the audio playback device (and/or a microphoneof the audio playback device) does not have a frequency response for asubset of the range of frequencies (e.g., the response is substantiallyzero) while the transfer function H of other audio playback devices(and/or a microphone of the audio playback device) in the environment dohave a frequency response for the subset of the range of frequencies(e.g., the response is substantially non-zero), then the audio playbackdevice may be impaired such that calibration cannot be performed. Tofacilitate determining whether the audio playback device is impaired,the network device performing the calibration may receive from an audioplayback device, computing device, or NMD the transfer function H of oneor more audio playback also in the environment.

Methods and the other processes disclosed herein may include one or moreoperations, functions, or actions. Although the blocks are illustratedin sequential order, these blocks may also be performed in parallel,and/or in a different order than those described herein. Also, thevarious blocks may be combined into fewer blocks, divided intoadditional blocks, and/or removed based upon the desired implementation.

In addition, for the methods and other processes disclosed herein, theflowchart shows functionality and operation of one possibleimplementation of present embodiments. In this regard, each block mayrepresent a module, a segment, or a portion of program code, whichincludes one or more instructions executable by a processor forimplementing specific logical functions or steps in the process. Theprogram code may be stored on any type of computer readable medium, forexample, such as a storage device including a disk or hard drive. Thecomputer readable medium may include non-transitory computer readablemedium, for example, such as computer-readable media that stores datafor short periods of time like register memory, processor cache andRandom Access Memory (RAM). The computer readable medium may alsoinclude non-transitory media, such as secondary or persistent long termstorage, like read only memory (ROM), optical or magnetic disks,compact-disc read only memory (CD-ROM), for example. The computerreadable media may also be any other volatile or non-volatile storagesystems. The computer readable medium may be considered a computerreadable storage medium, for example, or a tangible storage device. Inaddition, each block in the figures may represent circuitry that iswired to perform the specific logical functions in the process.

IV. Conclusion

The description above discloses, among other things, various examplesystems, methods, apparatus, and articles of manufacture including,among other components, firmware and/or software executed on hardware.It is understood that such examples are merely illustrative and shouldnot be considered as limiting. For example, it is contemplated that anyor all of the firmware, hardware, and/or software aspects or componentscan be embodied exclusively in hardware, exclusively in software,exclusively in firmware, or in any combination of hardware, software,and/or firmware. Accordingly, the examples provided are not the onlyway(s) to implement such systems, methods, apparatus, and/or articles ofmanufacture.

Additionally, references herein to “embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment can be included in at least one example embodiment of aninvention. The appearances of this phrase in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments mutually exclusive of otherembodiments. As such, the embodiments described herein, explicitly andimplicitly understood by one skilled in the art, can be combined withother embodiments.

The specification is presented largely in terms of illustrativeenvironments, systems, procedures, steps, logic blocks, processing, andother symbolic representations that directly or indirectly resemble theoperations of data processing devices coupled to networks. These processdescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art. Numerous specific details are set forth to provide athorough understanding of the present disclosure. However, it isunderstood to those skilled in the art that certain embodiments of thepresent disclosure can be practiced without certain, specific details.In other instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring aspects of the embodiments. Accordingly, the scope of thepresent disclosure is defined by the appended claims rather than theforgoing description of embodiments.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible,non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on,storing the software and/or firmware.

1. A first playback device of a playback environment, the first playbackdevice comprising: at least one processor; a non-transitorycomputer-readable medium; at least one microphone; and programinstructions stored on the non-transitory computer-readable medium thatare executable by the at least one processor such that the firstplayback device is configured to: receive a first stream of audiocomprising source audio content to be played back by a second playbackdevice of the playback environment; record, via the at least onemicrophone, an audio signal output by the second playback device basedon the second playback device playing back the source audio content;determine a transfer function between a frequency-domain representationof the first stream of audio and a frequency-domain representation ofthe recorded audio signal; based on a difference between (i) thetransfer function and (ii) a test response of the second playbackdevice, determine an estimated frequency response of the second playbackdevice in the playback environment; based on the estimated frequencyresponse of the second playback device in the playback environment,determine an acoustic calibration adjustment for the second playbackdevice; and cause the second playback device to implement the acousticcalibration adjustment.
 2. The first playback device of claim 1, whereinthe first playback device is located in a first spatial location of theplayback environment and the second playback device is located in asecond spatial location different from the first spatial location. 3.The first playback device of claim 2, wherein the test responsecomprises a response of the second playback device at the first spatiallocation of the first playback device.
 4. The first playback device ofclaim 1, wherein the program instructions stored on the non-transitorycomputer-readable medium that are executable by the at least oneprocessor such that the first playback device is configured to determinea transfer function comprise program instructions stored on thenon-transitory computer-readable medium that are executable by the atleast one processor such that the first playback device is configuredto: transmit, to a computing device, at least the recorded audio signal;and receive, from the computing device, the transfer function.
 5. Thefirst playback device of claim 1, wherein the program instructions thatare executable by the at least one processor such that the firstplayback device is configured to receive the first stream of audiocomprise program instructions that are executable by the at least oneprocessor such that the first playback device is configured to: receivemusic content from a cloud-based music service provider.
 6. The firstplayback device of claim 1, further comprising program instructionsstored on the non-transitory computer-readable medium that areexecutable by the at least one processor and thereby cause the firstplayback device to be configured to: determine that the second playbackdevice has changed at least one of (a) spatial location or (b)orientation; and wherein the program instructions that are executable bythe at least one processor such that the first playback device isconfigured to determine the estimated frequency response of the secondplayback device comprise program instructions that are executable by theat least one processor such that the first playback device is configuredto: calculate the estimated frequency response in response todetermining that the second playback device has changed at least one of(a) spatial location or (b) orientation.
 7. The first playback device ofclaim 1, further comprising program instructions stored on thenon-transitory computer-readable medium that are executable by the atleast one processor such that the first playback device is configuredto: determine a spectral coverage of the source audio content prior tocalculating the estimated frequency response of the second playbackdevice.
 8. The first playback device of claim 1, wherein the programinstructions that are executable by the at least one processor such thatthe first playback device is configured to cause the second playbackdevice to implement the acoustic calibration adjustment comprise programinstructions that are executable by the at least one processor such thatthe first playback device is configured to: cause the second playbackdevice to implement the acoustic calibration adjustment during playbackof the source audio content by the second playback device.
 9. The firstplayback device of claim 1, wherein the program instructions that areexecutable by the at least one processor such that the first playbackdevice is configured to determine an acoustic calibration adjustment forthe second playback device comprise program instructions that areexecutable by the at least one processor such that the first playbackdevice is configured to: select an audio processing algorithm from adatabase of audio processing algorithms stored in a memory of the firstplayback device.
 10. The first playback device of claim 1, wherein theprogram instructions that are executable by the at least one processorsuch that the first playback device is configured to determine anacoustic calibration adjustment for the second playback device compriseprogram instructions that are executable by the at least one processorsuch that the first playback device is configured to: calculate an audioprocessing algorithm based on the estimated frequency response of thesecond playback device.
 11. The first playback device of claim 10,wherein the program instructions that are executable by the at least oneprocessor such that the first playback device is configured to calculatean audio processing algorithm based on the estimated frequency responseof the second playback device comprise program instructions that areexecutable by the at least one processor such that the first playbackdevice is configured to: apply, to the source audio content, one or bothof a filter setting or an equalization setting.
 12. The first playbackdevice of claim 1, further comprising program instructions stored on thenon-transitory computer-readable medium that are executable by the atleast one processor such that the first playback device is configuredto: determine that the second playback device has been configured in abonded zone with at least a third playback device for synchronousplayback of separate channels of the source audio content, wherein theprogram instructions that are executable by the at least one processorsuch that the first playback device is configured to determine theestimated frequency response of the second playback device compriseprogram instructions that are executable by the at least one processorsuch that the first playback device is configured to: determine theestimated frequency response of the second playback device in responseto determining that the second playback device has been configured in abonded zone with at least the third playback device.
 13. The firstplayback device of claim 1, wherein the program instructions that areexecutable by the at least one processor such that the first playbackdevice is configured to determine an acoustic calibration adjustment forthe second playback device further comprise program instructions thatare executable by the at least one processor such that the firstplayback device is configured to: before determining the acousticcalibration adjustment for the second playback device: determine thatthe second playback device is unable to be calibrated; provide, via auser interface, an option to re-attempt calibration of the secondplayback device; and based on receiving an indication of a user inputselecting the option to re-attempt calibration of the second playbackdevice, provide, via the user interface, an instruction for user action.14. The first playback device of claim 13, wherein the instruction foruser action comprises an instruction for the user to (a) move the secondplayback device to a different spatial location of the playbackenvironment and (b) confirm that the second playback device has beenmoved.
 15. A non-transitory computer-readable medium, wherein thenon-transitory computer-readable medium is provisioned with programinstructions that, when executed by at least one processor, cause afirst playback device of a playback environment to: receive a firststream of audio comprising source audio content to be played back by asecond playback device of the playback environment; record, via the atleast one microphone, an audio signal output by the second playbackdevice based on the second playback device playing back the source audiocontent; determine a transfer function between a frequency-domainrepresentation of the first stream of audio and a frequency-domainrepresentation of the recorded audio signal; based on a differencebetween (i) the transfer function and (ii) a test response of the secondplayback device, determine an estimated frequency response of the secondplayback device in the playback environment; based on the estimatedfrequency response of the second playback device in the playbackenvironment, determine an acoustic calibration adjustment for the secondplayback device; and cause the second playback device to implement theacoustic calibration adjustment.
 16. The non-transitorycomputer-readable medium of claim 15, wherein the first playback deviceis located in a first spatial location of the playback environment andthe second playback device is located in a second spatial locationdifferent from the first spatial location.
 17. The non-transitorycomputer-readable medium of claim 16, wherein the test responsecomprises a response of the second playback device at the first spatiallocation of the first playback device.
 18. The non-transitorycomputer-readable medium of claim 15, wherein the program instructionsthat, when executed by at least one processor, cause the first playbackdevice to determine a transfer function comprise program instructionsstored on the non-transitory computer-readable medium that, whenexecuted by at least one processor, cause the first playback device to:transmit, to a computing device, at least the recorded audio signal; andreceive, from the computing device, the transfer function.
 19. Thenon-transitory computer-readable medium of claim 15, wherein thenon-transitory computer-readable medium is also provisioned with programinstructions that, when executed by at least one processor, cause thefirst playback device to: determine that the second playback device haschanged at least one of (a) spatial location or (b) orientation; andwherein the program instructions that, when executed by at least oneprocessor, cause the first playback device to determine the estimatedfrequency response of the second playback device comprise programinstructions stored on the non-transitory computer-readable medium that,when executed by at least one processor, cause the first playback deviceto: calculate the estimated frequency response in response todetermining that the second playback device has changed at least one of(a) spatial location or (b) orientation.
 20. A method carried out by afirst playback device of a playback system, the method comprising:receiving a first stream of audio comprising source audio content to beplayed back by a second playback device of the playback environment;recording, via the at least one microphone, an audio signal output bythe second playback device based on the second playback device playingback the source audio content; determining a transfer function between afrequency-domain representation of the first stream of audio and afrequency-domain representation of the recorded audio signal; based on adifference between (i) the transfer function and (ii) a test response ofthe second playback device, determining an estimated frequency responseof the second playback device in the playback environment; based on theestimated frequency response of the second playback device in theplayback environment, determining an acoustic calibration adjustment forthe second playback device; and causing the second playback device toimplement the acoustic calibration adjustment.